1. Technical Field
The present invention relates to an improved method for the production of potato chips and more particularly to a method for making potato chips which are similar in taste and texture to prior art potato chips produced by a traditional process but with less fat content.
2. Description of Related Art
Commercial production of potato chips typically involves a continuous process wherein sliced potatoes are continuously introduced into a vat of frying oil at a temperature of about 365° F. (about 185° C.) or higher, conveyed through the oil by paddles or other means, and removed from the oil after about two and one-half to three minutes of frying by an endless conveyor belt when the moisture content of the chips has been reduced to about 2% by weight or less. The resulting product generally has texture and flavor characteristics which are usually recognizable by consumers as typical commercially produced continuous process potato chips.
The typical steps used in making prior art potato chips in this manner involve first peeling the potatoes, then slicing the potatoes, washing and/or blanching the potato slices, drying the potato slices, and then frying the potato slices by emersion in an edible oil or fat heated at an appropriate temperature. After frying, the potato chips can be seasoned with salt and other seasonings and packaged for sale to consumers. Potato chips manufactured in this way typically comprise 30% to 40% or even higher fat content by weight. This fat is picked up during the frying process when the chips are immersed in edible oil or fat and cooked.
The oil content of potato chips is important for many reasons. Most important is its contribution to the overall organoleptic desirability of potato chips, however from the standpoint of good nutrition, it is desirable to maintain a low level of oil or fat in chips. Further, a high oil content renders the chips greasy or oily and hence less desirable to consumers. On the other hand, it is possible to make chips so low in oil that they lack flavor and seem harsh in texture. A happy medium can be achieved by reducing the oil content in a chip so that the objectives of using less oil is met and consumers interested in reducing their intake of both fats and calories can be satisfied with an organoleptically pleasing snack food.
Numerous attempts have been made in the prior art to reduce the oil content in potato chips. Some attempts involve pre-treating the potato slices prior to frying. Other attempts involve treating the chips after frying, and some attempts use both pre- and post-treatments. However, past attempts at producing lower oil content chips are either expensive, or have failed to maintain the desired organoleptical properties such as taste and texture that have become familiar to consumers of traditional potato chips having higher fat or oil contents.
For example, U.S. Pat. No. 4,749,579 teaches a process for producing potato chips having a fat content lower than 32% by weight. The '579 Patent discloses a pre-treatment process whereby potato slices are washed in a salt or brine solution. The potato slices are dried and potato slices are pre-heated with infrared radiation prior to being sent to the fryer. This process however has been proven to reduce fat in the end product very inconsistently. The '579 Patent even discloses that the resultant chip has a fat content in the range of 26% to 32% by weight compared with a prior art oil content of 38%. Further, the '579 Patent requires an infrared radiation step, thus adding equipment and processing expenses.
Another prior art attempt for making a low oil potato chip by pre-fry treatment is disclosed by U.S. Pat. No. 4,917,919, which teaches coating a potato chip with an aqueous, polyvinylpyrrolidone. Unfortunately, the moisture content of the finished product is about 4% by weight, raising concerns of shelf stability.
U.S. Pat. No. 4,933,199, assigned to the same Assignee as the present invention, involves treating a fried potato chip in a de-oiling unit to lower the oil content of the chip and further treating the chip in a dehydrating unit to lower the moisture content of the chip. Unfortunately, each unit operation can add substantial capital costs as well as operating cost to the process. Further, the '199 Patent indicates that attempting to de-oil potato slices to produce low oil potato chips and simultaneously arrive at a desired final moisture content has been found to be difficult to achieve in the same unit. The '199 Patent indicates that optimized de-oiling and optimized final moisture content are not arrived at simultaneously.
Similarly, U.S. Pat. No. 4,721,625 uses a post-fry saturated steam treatment to reduce the oil content of the potato slices. A saturated steam blasting process, however, generally results in a pick up of moisture by the cooked slices due to condensation. As a result, the cooked slices require a subsequent drying unit operation. As previously indicated, this subsequent drying operation involves substantial economic capital and operating outlays.
Another prior art solution to making a low oil potato chip is illustrated by U.S. Pat. No. 4,537,786, also assigned to the same Assignee as the present invention. The '786 Patent teaches that thicker than normal slicing can reduce oil uptake during frying. The '786 Patent process discloses: frying potato slices in oil at a lower than normal temperature of between about 280° F. and 320° F., removing the potato slices from the fryer when the moisture content is about 3% to about 15% by weight, orienting the potato slices on edge, and contacting the fried potato slices for about 1 to about 10 minutes with a stream of hot air. This hot air removes the excess oil as well as finishes cooking the chip. However, hot air tends to accelerate oxidation of the oil reducing shelf life dramatically.
Another prior art solution for a low oil potato chip is disclosed in U.S. Pat. No. 4,277,510, a process for making low oil potato chips by drying the slices in a monolayer, contacting the resultant dried potato slices with steam, and frying the steam-treated potato slices. Unfortunately, according to U.S. Pat. No. 4,721,625 (discussed above), the pre-drying of the product in the '510 Patent results in a glassy texture, case hardened product that has a raw, green flavor, which is different in taste and texture from regularly fried potato chips.
Several other efforts have been made to reduce the fat in potato chips by limiting the exposure to frying in oil and even by baking the chips and then seasoning them to attempt to produce a chip that is acceptable to consumers used to eating fried potato chips. These efforts have met with limited success, often involving expensive non-traditional processing steps or resulting in a product that does not provide similar desirable characteristics as compared to a fried potato chip.
Consequently, there is a need in the industry for an efficient process for making a reduced-fat potato chip which uses existing equipment, adds little to the cost of producing the chip, yet produces a potato chip that is quite similar in characteristics to a potato chip produced by a standard prior art method.